Generally, an ink-jet head includes a plurality of nozzles, a plurality of ink chambers which are provided so as to respectively communicate with the respective nozzles, and a plurality of actuators which individually change volumes of the respective ink chambers. An ink flow path which includes a nozzle and an ink chamber communicating with the nozzle is referred to as a channel. Piezoelectric members are used as the actuators. An electrode is attached to each piezoelectric member, and drive voltage with predetermined drive waveforms is applied to electrodes at both ends of the piezoelectric member arranged between a channel as a target of ink ejection and a channel adjacent to the channel. If the drive voltage is respectively applied to the electrodes at both ends, the piezoelectric member performs a deforming operation in accordance with a potential difference between the electrodes at both ends. The volume of the ink chamber in the channel as a target of ink ejection varies due to the deforming operation, and ink in the ink chamber is ejected from the nozzle due to the variation in the volume.
Incidentally, there is a case where potential applied to the electrodes at both the ends of the piezoelectric member simultaneously changes in a same direction out of a positive direction and a negative direction, depending on an application pattern of the drive voltage. At this time, the piezoelectric member does not act as load capacity and is brought to be in an unloaded state. If the piezoelectric member is in the unloaded state, voltage applied to the electrodes of the piezoelectric member steeply changes. Such a steep change in the voltage causes a noise and becomes a cause for erroneous operation.
In the related art, a technique for suppressing a steep change in voltage applied to electrodes of a piezoelectric member by controlling the voltage applied to the electrodes of the high-impedance piezoelectric member while the potential applied to the electrodes at both ends of the piezoelectric member simultaneously changes in the same direction out of a positive direction and a negative direction is known as a technique for reducing such noise.
According to such a technique in the related art, however, it is necessary to prepare, for each channel drive circuit, a detection circuit for detecting that the potential applied to the electrodes at both the ends of the piezoelectric member simultaneously changes in the same direction out of the positive direction and the negative direction. Therefore, since many detection circuits are required in a case of an ink-jet head of multiple channels, there is a concern that an Integrated Circuit (IC) increases in size, which results in an increase in cost, in consideration of configuring the IC of a drive device in which respective channel drive circuits are integrated.